1. Field of the Invention
The disclosed device relates to energy storage. More particularly, the disclosure relates to a system and method for storing energy generated from natural sources such as wind and sun which have an energy generation output which is inherently variable. Through the employment of such natural energy production to generate and store negative air pressure, renewable energy from peak periods of production which may be mismatched to a minimized requirement of a power grid, may be stored and communicated to the grid as needed or to supplement periods of low generation by a solar array or windmill farm.
2. Prior Art
A longstanding vexation is the fact that the value of two prominent renewable energy sources is compromised by their irregular nature. Wind is inherently variable. Some days are windy, some are not, and even during a single day wind varies throughout the day. Consequently, a mismatch frequently occurs between potential energy available from low winds during periods of peak demand, and high winds during periods when the demands of the electrical grid may be low, such as in the evening. Further, due to the nature of wind farms being located distant to cities requiring energy, at times the power generated in wind farms can exceed the capacity of the transmission lines communicating the power to the grid requiring it. Unable to transmit the power generated during peak winds, frequently windfarms will idle turbines which could be producing electrical energy at a maximum rate.
Solar energy suffers its own constraints. First, solar energy is only produced during the day, which may be advantageous in the summer when consumer air-conditioning demands peak during the day. However, in other months of the year, the periods of peak demand are in the early mornings and evenings when little or no solar power is produced. Thus, energy on such solar farms available at mid day may go unused due to a lack of demand of the power grid. Additionally, solar energy farms also are frequently located a good distance from the power grids they serve and transmission lines can limit the amount of power that may be communicated from the solar generation facility to the distant grid. If transmission lines lack the capacity to transmit the full amount of power a solar generation facility can produce at mid day in bright sunlight, the energy can go to waste.
Means for cost effective power storage have long been sought to mitigate these problems and add value to the naturally generated and captured energy. Benefits of storage are significant, especially in integrating distributed generation. Energy storage provides potential energy which may be tapped to balance production with demand peaks and to deter the need for power transmission and grid upgrades.
Power storage devices in common use today are pumped-hydro, compressed air, flywheels, and batteries. Pumped-hydro storage as described in U.S. Pat. Nos. 7,239,035, 6,023,105, and 4,380,419 has played an important role in enhancing grid system stability for over a century, however wider use of pumped-hydro storage is limited by requiring sites with strong winds for power generation and access to vertically disparate water reservoirs. Compressed air energy storage is offered in many forms as exemplified in U.S. Pat. Nos. 7,254,944, 4,447,738, and 4,237,692 but requires means to compensate for diabatic thermal energy leakage which compromises this type of storage. Flywheels and batteries have specialized uses but neither can offer cost effectiveness for bulk energy storage as would be needed for grid-connected solar and wind farms.
Small renewable energy systems have been promoted to reduce farm, business, and domestic energy bills but complete independence from electric utilities would only be practical if there was a cost effective way to store a significant amount of power from peak generation periods, on site or nearby, to supplement power generated during minimal generation periods.
Further, current grids must maintain “peaker plants” to input energy during periods of high demand when the generation capacity to the grid is maximized. Such peaker plants are located throughout cities and energized during periods of high demand to keep the grid from overloading. However, they are noisy, and generally run by diesel engines which pollute and must have onsite supplies of fuel which must be maintained. A storage device allowing excess produced energy from the grid to simply be stored and injected back to the grid as needed which is small and non polluting would be a boon to such grid systems.
As such, there is an unmet need for an energy storage system that addresses the shortcomings and limitations of conventional energy storage systems. Such a system should allow wind generation systems to maximize energy production at all times of peak wind, no matter the demand for the energy or the transmission line capability. Such a system should also be adapted to store solar generated energy during peak sunlight periods irrespective of grid demand and transmission capability. Further, such a system should be sufficiently compact and low-tech to be deployable on a small farm or business or residential property to allow for energy storage during peak periods to supplement minimal production periods. Such a system should also be able to substitute for the conventional diesel or gas powered peaker plants most grids maintain.
The apparatus and method herein is adapted to overcome these shortcomings and meet these objectives. The system employs a contained negative pressure reservoir or vacuum which is generated in real time from the natural energy production facility, and allows for energy storage for future use. It is an easy to maintain system not requiring a high degree of technical expertise and well adapted for employment by large energy farms, smaller business and residential properties having onsite renewable energy generation.
In this respect, before explaining at least one embodiment of the herein disclosed energy storage apparatus and method of operation invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangement of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways.
Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting. As such, those skilled in the art will appreciate that the conception, upon which this disclosure is based, may readily be utilized as a basis for designing other storage systems for renewable energy and for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent construction insofar as they do not depart from the spirit and scope of the present invention.
An object of this invention is the provision of such a storage system for wind energy or solar energy which does not require batteries or other electrical means for energy storage, yet will produce electrical energy as needed.
It is a further object of the invention herein, to provide such a renewable energy storage system which will allow windmill farms and solar energy generation facilities to operate more profitably by allowing for storage of energy produced during peak available generation periods for sale and use at times when grid requirements and/or prices are higher.
Yet another object of the invention herein is to provide such a renewable energy storage system and method, that is deployable on a small scale such as on ranches and residential properties having windmills and solar generation to provide a means to even out energy production with usage over a period of time.
A further object of this invention is to provide means to store unreliable intermittent power to increase its usefulness and value.
Another object of the invention herein is the provision of a cost effective in kilowatt-hour storage capacity.
An additional object of the disclosed invention is the provision of such an energy storage facility which may be readily constructed with low cost concrete and can be sited anywhere with access to grid transmission lines.
A further object of the invention herein disclosed is that it may be continually upgraded to be sized as needed and which is effective for both long term and short term energy storage.
Yet a further object of the disclosed device and method for energy storage herein is that it is not subject to thermal energy loss.
Yet another object of this invention is the provision of a means to store excess produced electricity from normal grid generation plants and feed it to the grid when peak demand requires and thereby replace expensive and polluting peaker plants.
Finally, yet another object of the invention herein is a mode of energy storage that may be easily adapted to non manmade structures for negative pressure containment in the form of terrestrial cavities such as mines, wells and caverns.
These together with other objects and advantages which will become subsequently apparent reside in the details of the construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming a part thereof, wherein like numerals refer to like parts throughout.